Parkers overall rating: 4.4 out of 5 4.4

Miles per pound (mpp) Miles per pound (mpp)

Petrol engines 5.6 - 6.8 mpp
Diesel engines 7.0 - 9.0 mpp
Low figures relate to the least economical version; high to the most economical. Based on WLTP combined fuel economy for versions of this car made since September 2017 only, and typical current fuel or electricity costs.

Fuel economy

Petrol engines 36.2 - 44.1 mpg
Diesel engines 47.1 - 60.1 mpg
  • Diesels are supremely economical and efficient
  • BIK and CO2 figures are super-competitive
  • Should be reliable, if it performs like a 3 Series

The BMW 4 Series range is still growing, but the numbers are looking good for all petrol and diesel models, especially the lowered powered 420 models. Starting with the entry-level 420i, WLTP Combined economy comes in at between 42.2 and 44.1mpg in 'Sport Automatic' form. Move to the 420d and that figure rises to between 57.6 and 61.4mpg – again in 'Sport Automatic' form.

Watch: what are the real running costs?

Step up to the 430i which is available in M Sport Pro form only and the balance of performance and economy changes a little. The petrol-powered 430i makes 39.8-42.2mpg, which is a great result for a car with this level of performance. Finally, the 375hp BMW M440i xDrive puts in a great performance, too, making 33.1-34.6mpg WLTP Combined.

Emissions are very competitive, too. The best performer is the 420d, producing 121-129g/km of CO2 with a BIK rating of 27-28%. That rises to 146-153g/km for the 420i and 153-161g/km for the 430i. That's pretty much identical to the range-topping M440i, which puts in a great performance to post 155-161g/km.


  • The 4 Series should match the 3's reliability record
  • Three-year warranty as standard
  • BMW finished last in 2019 JD Power survey

The 4 Series is based heavily on the 3 Series, and that car is well-regarded in terms of reliability. This model uses some new infotainment technology which we’ve found to be patchy in operation – but it's improving with dealer updates proving effective.

Otherwise, mechanical components are tried and tested from a vast range of other BMW cars, and the 3 and 5 Series continue to perform well, finishing just behind the Honda Civic, in the Fleet News FN50 reliability survey.

However, this is tempered by BMW's poor performance in the 2019 JD Power UK Vehicle Dependancy Survey. The organisation measures the number of problems experienced per 100 vehicles (PP100), to come up with a score, with a lower number indicating better performance. BMW came bottom of the heap with a score of 181, compared with 167 for Audi and 137 for Mercedes-Benz.

BMW 4 Series (2020) boot badge

Ongoing running costs

Road tax (12 months) £490
Insurance group 30 - 42
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